title: Changes in intestinal permeability after Roux-en-Y gastric bypass.
abstract: BACKGROUND
  Roux-en-Y gastric bypass (RYGB) interferes considerably with the anatomy and physiology of the gastrointestinal tract. The study of intestinal permeability can provide important information regarding changes in the structure and function of the mucosal barrier after the procedure.
  
  
  METHODS
  The urinary excretion rates of lactulose and mannitol after oral intake of both substances were evaluated. We also evaluated the lactulose/mannitol excretion ratio. Tests were performed during the preoperative period (T0), at the first postoperative month (T1), and at the sixth postoperative month (T6).
  
  
  RESULTS
  The study included 16 morbidly obese patients. The excretion rate of mannitol was significantly lower at T1 compared with T0 and T6 (p = 0.003). There was no significant difference in the excretion rates of lactulose or in the lactulose/mannitol ratio during the three periods. Six patients (37.5%) exhibited a considerable increase in the excretion rate of lactulose at T6 (4-73 times higher than the preoperative value), accompanied by proportional variations in the lactulose/mannitol ratio.
  
  
  CONCLUSIONS
  The significant increase in mannitol excretion rate from T1 to T6 most likely reflects the occurrence of intestinal adaptation (mucosal hyperplasia), which would tend to minimize the malabsorption of macronutrients. A subgroup of patients who undergo RYGB exhibit pronounced increase in their intestinal permeability (assessed by the lactulose/mannitol ratio and the lactulose excretion rate) at T6.
authors.affiliation: Instituto Alfa de Gastroenterologia, Hospital das Clínicas, Universidade Federal de Minas Gerais, Avenida Bernardo Monteiro, 1397/802, 30150-281, Belo Horizonte, Minas Gerais, Brazil, alexandresavassi@hotmail.com.
authors.forename: Alexandre Lages
authors.initials: AL
authors.lastname: Savassi-Rocha
authors.forename: Marco Túlio Costa
authors.initials: MT
authors.lastname: Diniz
authors.forename: Eduardo Garcia
authors.initials: EG
authors.lastname: Vilela
authors.forename: Maria de Fátima Haueisen Sander
authors.initials: Mde F
authors.lastname: Diniz
authors.forename: Soraya Rodrigues de Almeida
authors.initials: SR
authors.lastname: Sanches
authors.forename: Aloísio Sales
authors.initials: AS
authors.lastname: da Cunha
authors.forename: Maria de Lourdes de Abreu
authors.initials: Mde L
authors.lastname: Ferrari
authors.forename: Henrique Oswaldo da Gama
authors.initials: HO
authors.lastname: Torres
authors.forename: Bruno Antonio
authors.initials: BA
authors.lastname: Maciente
authors.forename: Gabriela Santana
authors.initials: GS
authors.lastname: Ataliba
authors.forename: Paloma Maciel
authors.initials: PM
authors.lastname: Araújo
authors.forename: Taciana Bretas
authors.initials: TB
authors.lastname: Guerra
authors.forename: Inara Kellen Fonseca
authors.initials: IK
authors.lastname: Balbino
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D005260:Female; D015390:Gastric Bypass; D041981:Gastrointestinal Tract / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007792:Lactulose / Q000652:urine*; D008297:Male; D008353:Mannitol / Q000652:urine*; D009767:Obesity, Morbid / Q000601:surgery* / Q000652:urine; D010539:Permeability; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D008353:Mannitol; D007792:Lactulose